1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device comprising a multilayer wiring layer including a copper trench wiring layer and aluminum wiring formed thereon.
2. Description of the Related Art
A non-volatile semiconductor memory is given as one of semiconductor memory devices. Recently, the non-volatile semiconductor memory has come to wide use as a device for storing data. Typically, a NAND type flash memory has known as an electrically rewritable non-volatile memory using a floating gate electrode.
As the NAND type flash memory has the advantage of scale-down, its storage capacity is increasing. Currently, in the NAND type flash memory, a multilayer wiring including a wiring formed of aluminum as a main component (Al wiring) is used. The lower layer of Al wiring and the upper layer of Al wiring are connected via a plug formed of Al as a main component (Al plug).
This kind of Al wiring and Al plug are formed the following process (Jpn. Pat. Appln. KOKAI Publication No. 11-330236).
First, an interlayer insulating film is formed on the lower-layer Al wiring. Thereafter, a resist pattern for forming a connection hole (via hole) is formed on the interlayer insulating film.
Next, the interlayer insulating film is etched using the resist pattern as a mask, and thereby, the connection hole is formed.
Next, an Al film is formed on the entire surface by reflow sputtering process. The connection hole is filled with the Al film.
Next, a resist pattern is formed on the Al film, the Al film is etched using the resist pattern as a mask, and thereby, an Al plug comprising the Al film and the upper-layer al wiring are formed.
It is expected that the scale-down of the NAND type flash memory advances. In this case, the present Al wiring has large resistance. For this reason, it is expected that a multilayer wiring including a wiring formed of copper as a main component (Cu wiring) is used. However, the process of the NAND type flash memory comprising a multilayer wiring including Cu wiring has not been known thus far.